linux-kernel - [PATCH 5.8 71/99] arch/x86/lib/usercopy_64.c: fix __copy_user

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Message-Id: <20200929105933.225517229@linuxfoundation.org>
Date:   Tue, 29 Sep 2020 13:01:54 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mikulas Patocka <mpatocka@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dan Williams <dan.j.wiilliams@...el.com>,
        Jan Kara <jack@...e.cz>, Jeff Moyer <jmoyer@...hat.com>,
        Ingo Molnar <mingo@...hat.com>, Christoph Hellwig <hch@....de>,
        Toshi Kani <toshi.kani@....com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        Thomas Gleixner <tglx@...utronix.de>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>,
        Ingo Molnar <mingo@...e.hu>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 5.8 71/99] arch/x86/lib/usercopy_64.c: fix __copy_user_flushcache() cache writeback

From: Mikulas Patocka <mpatocka@...hat.com>

commit a1cd6c2ae47ee10ff21e62475685d5b399e2ed4a upstream.

If we copy less than 8 bytes and if the destination crosses a cache
line, __copy_user_flushcache would invalidate only the first cache line.

This patch makes it invalidate the second cache line as well.

Fixes: 0aed55af88345b ("x86, uaccess: introduce copy_from_iter_flushcache for pmem / cache-bypass operations")
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Dan Williams <dan.j.wiilliams@...el.com>
Cc: Jan Kara <jack@...e.cz>
Cc: Jeff Moyer <jmoyer@...hat.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Christoph Hellwig <hch@....de>
Cc: Toshi Kani <toshi.kani@....com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Matthew Wilcox <mawilcox@...rosoft.com>
Cc: Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: <stable@...r.kernel.org>
Link: https://lkml.kernel.org/r/alpine.LRH.2.02.2009161451140.21915@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/lib/usercopy_64.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/lib/usercopy_64.c
+++ b/arch/x86/lib/usercopy_64.c
@@ -120,7 +120,7 @@ long __copy_user_flushcache(void *dst, c
 	 */
 	if (size < 8) {
 		if (!IS_ALIGNED(dest, 4) || size != 4)
-			clean_cache_range(dst, 1);
+			clean_cache_range(dst, size);
 	} else {
 		if (!IS_ALIGNED(dest, 8)) {
 			dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);